In musical instruments, specifically in the category of instruments known as brass instruments, air is directed through a tubing path in order to produce fundamental pitches. For many instruments, valves are located in the tubing path, which when actuated, direct air through alternate paths of tubing, or crooks, before allowing the air to be directed back through the main path. Use of these valves allows the musician to quickly change the overall length of the tubing path, thus allowing the musician to quickly change the fundamental pitch of the instrument.
Each valve contains multiple openings that can be aligned with openings in the main tubing path and alternate tubing paths. By applying pressure to a valve's finger button, the valve's piston will be displaced and the openings in the valve are moved to a desired position. For example, when the valve is not actuated, air may pass from the main tubing path, through a first set of openings, and continue through the remainder of the main tubing path. However, when a valve's finger button is depressed, the valve can be moved so that air passing from the main tubing path into the valve will pass into a second set of openings, continue through an alternate tubing path, and then back into the valve and out through the remainder of the main tubing path.
Variations in alignment between the openings of the valve and the openings of the main tubing path and alternate tubing paths can cause effects in the sound produced by the instrument, the amount of backpressure experienced by a musician, and other effects. Misaligned valves can result in a change of clarity of the sound, a change in the sound of how a note begins or ends, a change in the energy of the sound, change in waveform reflections within the instruments, as well as other changes.